for

for

loops are the most complex loops in PHP. They behave like their C counterparts. The syntax of a loop is:

`for``for````php for (expr1; expr2; expr3) statement

  The first expression () is
  evaluated (executed) once unconditionally at the beginning of the
  loop.
 `expr1`


  In the beginning of each iteration,
   is evaluated.  If it evaluates to
  true, the loop continues and the nested
  statement(s) are executed.  If it evaluates to
  false, the execution of the loop ends.
 `expr2`


  At the end of each iteration,  is
  evaluated (executed).
 `expr3`


  Each of the expressions can be empty or contain multiple
  expressions separated by commas. In , all
  expressions separated by a comma are evaluated but the result is taken
  from the last part.
   being empty means the loop should
  be run indefinitely (PHP implicitly considers it as
  true, like C).  This may not be as useless as
  you might think, since often you'd want to end the loop using a
  conditional 
  statement instead of using the  truth
  expression.
 `expr2``expr2`break`for`


  Consider the following examples.  All of them display the numbers
  1 through 10:
  
 ```php
<?php
/* example 1 */

for ($i = 1; $i <= 10; $i++) {
    echo $i;
}

/* example 2 */

for ($i = 1; ; $i++) {
    if ($i > 10) {
        break;
    }
    echo $i;
}

/* example 3 */

$i = 1;
for (; ; ) {
    if ($i > 10) {
        break;
    }
    echo $i;
    $i++;
}

/* example 4 */

for ($i = 1, $j = 0; $i <= 10; $j += $i, print $i, $i++);
?>

Of course, the first example appears to be the nicest one (or perhaps the fourth), but you may find that being able to use empty expressions in loops comes in handy in many occasions. for

PHP also supports the alternate "colon syntax" for loops.

`for````php for (expr1; expr2; expr3): statement ... endfor;

It's a common thing to many users to iterate through arrays like in the
  example below.


  
 ```php
<?php
/*
 * This is an array with some data we want to modify
 * when running through the for loop.
 */
$people = array(
    array('name' => 'Kalle', 'salt' => 856412),
    array('name' => 'Pierre', 'salt' => 215863)
);

for($i = 0; $i < count($people); ++$i) {
    $people[$i]['salt'] = mt_rand(000000, 999999);
}
?>

The above code can be slow, because the array size is fetched on every iteration. Since the size never changes, the loop be easily optimized by using an intermediate variable to store the size instead of repeatedly calling : count

<?php
$people = array(
   array('name' => 'Kalle', 'salt' => 856412),
   array('name' => 'Pierre', 'salt' => 215863)
);

for($i = 0, $size = count($people); $i < $size; ++$i) {
   $people[$i]['salt'] = mt_rand(000000, 999999);
}
?>